1. Field of the Invention
The present invention relates to a display, and in particular relates to an electrowetting display and a method for fabricating the same.
2. Description of the Related Art
Along with developments in photoelectric techniques, electrowetting displays have been disclosed, having high contrast ratio, fast response time, low power consumption and high resolution characteristics.
The Liquavista Company manufactures an electrowetting display. The electrowetting display comprises a substrate, a non-polar oil, a polar solution, a hydrophobic layer, and a hydrophilic rib, wherein the hydrophobic layer is formed on the substrate, the non-polar oil is formed on the hydrophobic layer and separated by the hydrophilic rib, and the polar solution is disposed on the non-polar oil. Operation of the electrowetting display is as follow. When no voltage is applied to the display, the non-polar oil is formed on the hydrophobic layer, so that the color displayed is that of the non-polar oil. When a voltage is applied to the display, the polar solution is attracted by the induced charges formed on hydrophobic layer, and the non-polar oil moves to one corner of the substrate, so that the color of the substrate is displayed.
European publication NO. WO 2005098524 provides an electrowetting display, wherein the display comprises a polar solution, oil, an upper substrate and a lower substrate. However, the oil is only separated by the ribs, thus an oil overflow problem sometimes occur.
US publication NO. 20060285067 disclose an electrowetting display, wherein closed structures are formed with large height (high aspect ratio) ribs. However, the high aspect ratio ribs results in a more complex fabrication process.
US publication NO. 20050151709 disclose an electrowetting display, wherein the ribs have an upper portion and a lower portion. The lower portion ribs are hydrophobic to help oil flow, and the upper portion ribs are hydrophilic to prevent the problem of oil overflow.
In general, the hydrophilic ribs are often formed on the hydrophobic structures. Thus, a adhesion problem of ribs occur and large area fabrication is difficult due to the large polarity difference between the ribs and the hydrophobic structures. Additionally, the problem of oil overflow is difficult to mitigate due to the poor hydrophilic character of the surface of hydrophilic ribs made of resin.
Thus, there is a need to develop an electrowetting display with improved ribs adhesion, mitigating the oil overflow problem.